Allocation of data on a disc like record carrier of the read only type, such as an audio CD or a video CD is done most frequently contiguously in order to guarantee seamless playback. Apparatuses for reproducing data stored on these carriers, are provided with data read buffers to enable a minimal amount of data read to be stored temporarily. In this manner a seamless flow of information is guaranteed even when no data is read from the carrier due to, for instance, a required displacement of a data reading head, such as an optical pick up unit. The size of these data read buffers is preferably kept low for obvious reasons of cost. Time for displacement of a data reading head is therefore restricted. This makes it troublesome, in case of a rewritable disc like carrier, to seamlessly read one program and writing another program simultaneously. If during switching between reading and writing the programs are recorded contiguously, a reading/writing head would have to jump across a large area of the disc.
U.S. Pat. No. 5,706,388 discloses a system for performing a reproducing operation of previously recorded video information without stopping a recording operation of information currently being received. Data is recorded in the receiving order in consecutive areas on a recording medium such as a hard disk drive or an optical disc. Two reception buffers and two reproduction buffers are provided to be able to record and reproduce data simultaneously. While the reproducing operation is performed, the digital data corresponding to the received information is continuously supplied to and stored in either of the reception buffers. When a predetermined amount of data has been reproduced and stored in the reproduction buffer, a read out operation of the reproduction buffer starts. At the same time, the recording/reproducing head returns to the last recording position for the data supplied from either of the reception buffers. When the predetermined amount of data is recorded on the recording medium, the reproducing/recording head moves again to the last reproducing position to reproduce the predetermined amount of data.
Data is recorded/reproduced on the recording medium in blocks on areas of the recording medium, the size of the areas corresponding to the capacity of the buffers. However, previously recorded areas are written contiguously, therefore the recording/reproducing head jumps across a large area of the recording medium during switching between recording and reproduction. This necessitates large and costly buffers.
The European patent application EP-A 081 184, discloses a disc of the read-only optical type with the data on one program stored in duplicate. In case a defect occurs in part of the data of a program, the corresponding part can be acquired from the duplicate version of the program. In order to limit the search time of an optical pick up unit for this duplicate date, the data of the two identical programs is stored in an interleaved manner, either in annular band or track interleaved manner. However, multiple programs will be stored serially after each other, each interleaved with their duplicates, also requiring large access times when reproducing one program and recording another program.
The U.S. Pat. No. 5,784,528 discloses a method for storing a real time bit stream of video objects on a read-only disc of the optical type, according to the DVD-format. This format allows storage of multi-angle scenes. A user is able to select particular scenes from a multi-scene period. The data of a multi-scene is stored in an interleaved manner to assure seamless data reproduction. However, a next bit stream of video objects is stored after the previous stored one.
The two last mentioned disclosures both describe data of one program stored interleaved on the recording medium in order to reduce jumping time of an optical pick up unit, either in case of defects or in case switching of scenes within one program. However, data of one program is stored contiguously after data of the previous program.
The U.S. Pat. No. 5,613,112 relates to method of managing recordable areas with respect to a disc like recording medium capable of recording data such as music data. The disc is of the magneto-optical type. Program data is recorded in segments comprising a track portion of several tracks in which data is recorded physically contiguous. In practice, the segments of one program may be spaced apart, leading to large access times. According to the disclosed method, the distance between the segments of one program is minimized, in order to reduce the access time. To this purpose the sequential segments are managed to be at locations as close to each other as possible.
Therefore, in practice, programs will also be stored as much as possible sequentially after each other.